Many processes require that a gas be bubbled into a liquid via a diffuser, and many forms of diffusers exist for this purpose. In general, smaller gas bubbles from the diffuser speed up the dissolving of the gas into a liquid, but a diffuser that forms smaller gas bubbles generally offers greater resistance to the gas flow and thus requires more energy. I prefer a diffuser that consumes as little energy as possible so that a low pressure is adequate to force the gas through the diffuser and disperse it into the liquid as fine bubbles. I also prefer that a fine bubble diffuser stay clean and unclogged, even if operated intermittently.
Commercially available diffusers generally do not meet these requirements. Ceramic diffusers, for example, can make fine bubbles but require a substantial gas pressure to do this. Also, if such diffusers are operated intermittently, as required for some processes, then liquid can enter and clog pores of the diffuser. Once liquid has seeped into the diffuser pores, forcing gas back through the diffuser to reestablish bubbling requires even more pressure, because driving liquid rather than gas through the diffuser pores takes more energy. Liquids seeping into diffuser pores can also carry contaminates such as particles or dissolved solids into the pores where they clog the diffuser.
In an effort to make a more efficient diffuser that consumes less energy and produces very fine bubbles, I investigated many possible materials. This led to a discovery of materials and requirements that perform very well as a diffuser, keeping the bubbles fine, consuming little energy, and keeping pores substantially clear of liquid or clogging material. The diffusers I prefer also resist: liquid backflow so that a separate valve for this purpose is not required.